High strength nonwoven barrier material

Abstract

The present invention is directed toward a method of making a composite structure including receiving a substantially planar nonwoven spunbond layer including a plurality of multicomponent fibers, thermally bonding the nonwoven spunbond layer at a first bond temperature, laying down a meltblown layer on top of the thermally bonded nonwoven spunbond layer to form an intermediate structure, and thermally bonding the intermediate structure at a second bond temperature to form a final composite structure. Composite structures including a spunbond layer and a meltblown layer, wherein the composite structure has a tensile strength of at least about 130 N/2.54 cm in both machine and cross directions, a tear strength of at least 3.0 N/2.54 cm, and an LRV of about 2.0 or higher are also provided herein.

What is claimed is: 
     
       1. A method of making a composite structure comprising:
 receiving a substantially planar nonwoven spunbond layer comprising a plurality of multicomponent fibers; 
 thermally bonding the nonwoven spunbond layer at a first bond temperature; 
 laying down a meltblown layer on top of the thermally bonded nonwoven spunbond layer to form an intermediate structure; 
 thermally bonding the intermediate structure at a second bond temperature to form a final composite structure, 
 wherein the first bond temperature is higher than the second bond temperature. 
 
     
     
       2. The method of  claim 1 , further comprising:
 receiving a second substantially planar nonwoven spunbond layer comprising a plurality of multicomponent fibers; 
 thermally bonding the second nonwoven spunbond layer at the first bond temperature; 
 laying down the second nonwoven spunbond layer on top of the meltblown layer prior to thermally bonding the intermediate structure. 
 
     
     
       3. The method of  claim 1 , wherein the multicomponent fibers are bicomponent fibers comprising an external fiber component and an internal fiber component; wherein said external fiber component enwraps said internal fiber component; said external fiber component having a lower melting temperature than said internal fiber component. 
     
     
       4. The method of  claim 3 , wherein the external fiber component is polyethylene or polypropylene. 
     
     
       5. The method of  claim 3 , wherein the internal fiber component comprises a polymer selected from the group consisting of polyesters and polyamides. 
     
     
       6. The method of  claim 3 , wherein the internal fiber component comprises a polymer selected from the group consisting of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polylactic acid (PLA), nylon 6, nylon 6/6, nylon 11, nylon 12, nylon 6/11, thermoplastic polyurethanes (TPUs) and thermoplastic elastomers (TPEs). 
     
     
       7. The method of  claim 1 , wherein the first bond temperature is about 140° C. to about 160° C. 
     
     
       8. The method of  claim 1 , wherein the second bond temperature is about 90° C. to about 130° C. 
     
     
       9. The method of  claim 1 , wherein the composite structure has an LRV value of about 2.0 or higher. 
     
     
       10. The method of  claim 1 , wherein the meltblown layer comprises a plurality of fibers comprising polyethylene or polypropylene.